Three U.S. citizens have joined Kurdish forces battling the Islamic State group in northern Syria, CNN reported Friday, citing a spokesperson for the Yekineyen Parastina Gel, or YPG -- an armed Kurdish group.

While the identities two of the Americans have not been revealed, one of them is believed to be 28-year-old Jordan Matson from Wisconsin, according to media reports. YPG spokesperson Redur Xelil said that Matson was fighting in the Jazaa area, in Syria's northeastern Hasaka province, according to Reuters.

Matson had earlier told his friends that he was joining a “private army” to fight the Islamic State group, Reuters reported Thursday.

“He told us… that he was getting hired by a private army and he let us know two to three months in advance…He told me he dropped his girlfriend and stopped looking for a job,” Miguel Caron, a friend of Matson’s, told Reuters.

The U.S. military also confirmed that a man named Jordan Matson had enlisted in the Army in and served from May 2006 to November 2007, according to CNN.

Meanwhile, airstrikes by the U.S.-led coalition continued in northern Syria and Iraq. Overnight airstrikes targeted Islamic State group-held areas in al-Mayadeen in the Deir al-Zour province, Manbij and Jarablus in northeastern Aleppo, and Tal Abyad in Raqqa, near the Turkish border, according to an Al Jazeera report.

Violent clashes between Kurdish forces and ISIS militants were also reported near the Syrian border town of Kobane on Friday. On Thursday, 16 militants of the Islamic State group and 7 YPG fighters were killed in the region, according to the Syrian Observatory for Human Rights. The protracted battle over the control of the Kurdish-populated town has reportedly led to an exodus of hundreds of thousands of refugees into Turkey since last month.